METHOD OF PIERCING AND MANDREL UNIT USING HYDROFORMING, AND PART AND STRUCTURE PRODUCED BY HYDROFORMING Russian patent published in 2011 - IPC B21D51/16 B21D26/02 B21D28/28 B21D39/00 

FIELD: process engineering.

SUBSTANCE: invention relates to production of parts for automotive exhaust gas systems, suspension systems, body assemblies etc. Proposed method comprises fitting initial metal pipe into split mould with piercing male mould. Inner pressure and pressing force are applied to metal pipe in pipe axial direction or inner pressure, for hydroforming. Section of metal pipe is pierced. Piercing male mould is used driven perpendicular to axis of metal pipe fitted in mould, or in inclined direction. Said male mould has central section and front section narrower than the former. Nut with ID exceeding OD of said front section and smaller than central section OD is arranged on front section. Front section is used to drive piercing male punch to pierce metal pipe section. Edges of pierced hole are pushed toward metal pipe inner surface. Said nut is fitted into metal pipe. Invention covers also the device for hydroforming and metal pipe piercing, metal pipe with nut fitted thereon and structure made up of said pipe.

EFFECT: reduced labour input, higher strength of pipe.

11 cl, 20 dwg